Cryptic visual

What is this? You may well ask.

Well, apparently, it's: "[a] projection of the 600-cell truncated to the edge midpoints. This may be called the rectified 600-cell or the ambo-600-cell. In four dimensions, it consists of 120 regular icosahedra and 600 regular octahedra, but in this three-dimensional projection, it lays on top of itself, so it is only half that complex, but it still requires plenty of pieces."

Why is it here?

Well, this is Froogville's 600th post. No, really?! Yes, I'm afraid so. Staggering, isn't it? Somewhat frightening...